1. Field of the Invention
The present invention relates to an insecticidal delivery composition made from one or more solid superabsorbent polymers with or without one or more liquid or solid insecticidal or noninsecticidal film-forming or surface active agents, ovicides, larvicides, pupicides, insecticides, biological control agents, pathogens, parasites, microbial control agents, insect growth regulators, conventional toxicants, pesticides, or other additives. The present invention also relates to a method of applying the insecticidal delivery compositon alone or with one or more active insecticidal ingredients to an aquatic environment having a natural population of aquatic environment insects, for the purpose of controlling that population of insects. The present invention also relates to the use of the insecticidal delivery composition for a pretreatment application to an aquatic insect dry habitat in order to control that population of aquatic insects that will breed when the insect habitat becomes flooded by rain or tides. This invention further relates to a facile method of combining two or more active insecticidal ingredients, one of which is a film-forming agent, on a superabsorbent insecticidal delivery composition for ground or aerial application. This manner of application makes possible the mixing of active insecticidal ingredients that would otherwise be difficult or substantially impossible to combine as joint or multiple action formulations for spray application.
2. General Background
In particular, the present invention is directed against mosquitoes that breed in permanent or semipermanent, natural or artificial, aquatic habitats. Mosquitoes of major importance to be controlled by the present invention are species of the genera of Aedes, Anopheles, Culex, Culiseta, Coquillettidia, Deinocerites, Manosonia, Psorophora, Uranotaenia, and Wyeomyia. It is the main objective of this invention to direct the use of the insecticidal delivery composition for the control of the immature aquatic stages of various species of mosquitoes before they become biting adults capable of being a nuisance and/or transmitting a disease. This technique is cost-effective and reduces the environmental and health hazards that can result when insecticides are extensively broadcast over large areas for the control of the adult stages.
In addition to mosquitoes, other species of aquatic environment insects such as biting and nonbiting midges, black flies, moth flies, crane flies, horse flies, deer flies, hover or flower flies can constitute a nuisance and often a health threat to humans and livestock. Thus, their growth as a population, if unchecked, can be detrimental. The medical and veterinary importance of various species of mosquitoes and other important aquatic environment insects are discussed in detail by Robert F. Harwood and Maurice T. James in "Entomology In Human and Animal Health," Seventh Edition, 1979, MacMillan Publishing Co., Inc., New York, N.Y., which is incorporated herein by reference. Therefore, the scope of the present invention also relates to the use of the insecticidal delivery composition with one or more active insecticidal ingredients for controlling various species of aquatic environment insects other than mosquitoes.
Compositions and methods for controlling and killing insects are well known. A number of patents discuss the use of pesticides or insecticides. U.S. Pat. No. 3,535,423 discloses a wettable powder pesticide concetrate that may be dispersed in water. This is described as allowing the otherwise insoluble pesticide to become soluble in water. U.S. Pat. No. 4,267,280 discloses controlled release pesticides and their preparation. These pesticides are described as polymers with a macro-molecular backbone and pendant groups having pesticidal groups chemically linked thereto and prepared by reacting a pesticide having a replaceable hydrogen with a multifunctional isocyanate to form an adduct which is then reacted with a polyol polymer substrate. U.S. Pat. Nos. 4,400,391 and 4,401,456 disclose the use of alginate gel beads to encapsulate bioactive materials to provide for their controlled release. The patents describe beads being made to either float or sink and they may contain insecticides. These beads are also described as acting as carriers to place the bioactive material near the target species, for example, a floating bead containing a herbicide releasing the herbicide in close proximity to floating aquatic weeds or the beads falling through foliage to release herbicide into the soil. U.S. Pat. No. 4,344,857 contains a disclosure that is similar to those immediately above; however it involves encapsulation by xanthate derivatives and does not disclose the ability to be used in conjunction with an aqueous environment.
A number of patents describe the use of substances other then pesticides to control the growth of insects. U.S. Pat. No. 4,053,627 discloses a controlled release system for juvenile hormones in aqueous environments. This is described as being accomplished with alginate gel discs comprising alginate, a solubilizing agent, and a salt which yields cations, and containing the juvenile hormone. U.S. Pat. No. 4,160,033 discloses a method for the control of mosquitoes by the use of film-forming materials. The method is disclosed as involving the use of a film of organic material which reduces the surface tension of the body of water, and subsequently causes the mosquito larvae and pupae to drown.
At the present time, application of film-forming agents for mosquito control is essentially limited to liquids. Easier and more efficient ground and aerial delivery techniques are proposed by utilizing the film-forming insecticidal delivery composition as dusts, pellets, granules, or briquets that can float or sink. See, for example, Levy et al, "Control of Immature Mosquitoes With Liquid and Solid Formulations of A Monomolecular Organic Surface Film", Proceedings and Papers of the Fiftieth Annual Conference of the California Mosquito and Vector Control Association, Inc., and the Thirty-Eighth Annual Meeting of the American Mosquito Control Association, Apr. 18-22, 1982, Sacramento, Calif., pp. 106-108.
Technical film-forming agents applied as conventional liquid sprays cannot penetrate dense vegetation at low application rates. Therefore, most of the costly insecticidal film-forming agent impinges on the vegetation and does not reach the water where the mosquitoes are breeding. In addition, the use of water as a diluent for application of large volumes for easier vegetative penetration without overdosing requires high speed agitation or the use of water injection systems to adequately suspend the film-forming agent in the water for accurate application rates. Formulation of at least one film-forming agent with superabsorbent polymer(s) of the present invention into an agglomerated solid, e.g., a dense pellet or granule, allows penetration through the vegetative canopy for release of the film-forming agent into the target aquatic habitat without the costly overdosing or mixing problems that can occur with liquid sprays. At present, liquid film-forming agents used for mosquito control are applied to the water surface only. Since the film-forming agent floats because of its specific gravity, it can be adversely affected or removed from the target habitat by drying, runoff, drainage, or constant wind fetch. Superabsorbent-based film-forming agent compositions of the present invention can be formulated to sink or float. Sinking formulations as granules could be evenly distributed over the habitat at the desired dosage and would slowly release film-forming agent to water surface where it can control immature mosquitoes without being as severely affected by inhibiting pressures such as runoff or wind fetch. In addition, formulations of superabsorbent polymer(s) and a film-forming agent of the present invention can effect a mechanism for slow or controlled release, thereby extending the field life or persistence of the surface film for a greater period of time than would be expected with a liquid film-forming agent. Certain superabsorbent polymer formulations of the present invention are expected to extend the field persistence of the liquid formulations and thereby assure that the number of costly insecticide treatments per habitat will be significantly reduced.
None of the prior art methods or compositions for controlling insect populations are without disadvantages. One major problem associated with many of the aforementioned compositions and methods of the prior art is their inability to simultaneously apply immiscible, or otherwise incompatible substances to the area to be treated. It has been found that while film-forming materials, when combined with diluents, ovicides, larvicides, pupicides, insecticides, pesticides, conventional toxicants, biological control agents, microbial control agents, pathogens, parasites, or insect growth regulators, may produce improved insect controlling efficacy over single active component formulations, problems with mixing the ingredients often result. Blends of Arosurf.RTM. MSF (a film-forming agent) and water or technical and/or water-base blends of Arosurf.RTM. MSF and various formulations of Bacillus thuringiensis var. israelensis (B.t.i), or Bacillus sphaericus or Abate.RTM. 4-E do not form homogeneous suspensions when casually mixed, and therefore required frequent and vigorous agitation. When allowed to stand, the components would separate into distinct phases because of the differences in their respective specific gravities, and/or the presence of incompatible inert formulation ingredients, and therefore these joint action formulations would require either a continuous agitation or a reagitation to effectively remix the components just prior to their application.
These mixing and remixing requirements make it very difficult to apply these liquid formulations by conventional means. To circumvent some of these problems, high pressure water injection systems have been developed. But, high pressure water injection requires high volumes of water to deliver the formulation. This, among other structural limitations, renders application of certain single, joint or multiple action formulations for insect population control difficult by helicopter. Helicopter application is often a must for both economic efficiency and because many aquatic environment insect breeding areas are not otherwise accessible.
While it may be possible to incorporate some known components, singly or jointly or multiply into a solid agglomerated matrix, these formulations have been found to lack the quick or controlled release ability and the ability to control both mosquito larvae and pupae simultaneously while effectively and spontaneously spreading the active ingredients over the target habitat.
Since other slid agglomerated insecticidal compositions do not have rapid self-spreading characteristics, they require even applications to assure that the active insecticidal ingredient(s) are uniformly dispersed in the aquatic habitat to assure effective control of the target insects that may be widely dispersed in the habitat. In addition, the other solid agglomerated insecticidal components usually affect only one immature developmental stage. The use of insecticidal delivery compositions made from one or more superabsorbent polymers of the present invention with a pupicidal film-forming agent (e.g., Arosurf.RTM.MSF) and larvicidal agent such as B.t.i. or Bacilus sphaericus have self-spreading potential and can kill mosquito larvae, pupae, or emerging adults rapidly in areas far removed from the initial points of application. Although Arosurf .RTM.MSF can kill mosquito larvae and pupae, their impact on larval populations is usually very slow.
No single or joint action solid agglomerated formulations are available that claim rapid larvicidal and pupicidal action and self-spreading characteristics. Commercial solid agglomerated formulations of Bacillus thuringiensis var. israelensis (Vectobac.RTM. G, Teknar.RTM.granules, Bactimos.RTM. briquets, Bactimos.RTM.granules or pellets,) Abate.RTM.(1-SG, 2-CG, 5-CG), Dursban.RTM. 10CR, Furadan.RTM.3, or Furadan 5 granules, and Altosid.RTM.briquets are available that have slow or quick immature stage kill potential, and/or fast or slow release characteristics; however, these do not have rapid multidevelopmental stage control potential, do not have self-spreading characteristics, are typically composed of only one active insecticidal ingredient that cannot be simply and rapidly detected or monitored under field conditions by insecticide applicators, and are composed of non-superabsorbent polymer materials. For example, The Altosid.RTM. briquet is an insect growth regulator formulation designed to sink and release effective levels of the chemical for approximately 30 days. Altosid.RTM.is released as the charcoal-like brique erodes. Treated larvae continue to develop normally to the pupal stage where they die. Bactimos.RTM. briquets are composed of cork-like matrices that float and release effective levels of B.t.i. for approximately 30 days where they kill mosquitoes only in the larval stage. In addition, most of the products mentioned will not kill late 4th instar mosquito larvae and, with the exception of Altosid.RTM. which kills the mosquito slowly when it reaches the pupal stage, none of the products will directly kill pupae or emerging adults.
The active ingredients of the aforementioned products in their standard formulations can be formulated on a superabsorbent polymer of the present invention to provide an alternate substrate (carrier), or more preferably can be formulated with one or more larvicidal/pupicidal film-forming agents such as Arosurf.RTM.MSF to provide a joint action formulation that kills larvae, pupae, or emerging adults rapidly, has spontaneous spreading ability for better distribution of the active ingredients throughout the target habitat, and has the ability to be chemically monitored in the target habitat to determine the presence or persistance of one or more active insecticidal components.
Compaction of the superabsorbent polymer matrix of the present invention has been shown to effect a slow-release mechanism for certain active ingredients. In addition, varying the ratio of different types of these superabsorbent polymers of the present invention that have differential water uptake characteristics (e.g., Water Lock.RTM. products) in a single compacted or agglomerated matrix may effect a mechanism to further enhance the slow-release of certain active insecticidal ingredients. In addition, the varying specific gravities (i.e., less than or greater than one) of the superabsorbent polymers of the present invention can be used to develop floating or sinking formulations for use in a variety of habitats to kill a variety of aquatic insect species.
Attempts have been made to incorporate film-forming agents such as those described in U.S. Pat. No. 4,160,033 on or in a variety of floating or submerged solid water soluble, erodible, and porous matrices such as sponges, reticulated polyurethane foam, agar, gelatin capsules, cork, vermiculite, zein, corn cob grits, charcoals, sand, clays, lignins, celite, wood chips, sawdust, cetyl or stearyl alcohols, and cellulose acetate or triacetates. However, these attempts have been unsuccessful because the combined matrix and film-forming agent was either too soft to handle and apply by conventional techniques, too hard to release a sufficient amount of the active film-forming agent for effective mosquito control, and/or the matrix could not be impregnated with a sufficient amount of the film-forming agent to permit application of the bulk material at rates that were practical for operational mosquito control.